Edit Question - KnowledgeHub

Title Body

I want to export a movie with AVAssetWriter and can't figure out how to include video and audio tracks in sync. Exporting only video works fine, but when I add audio the resulting movie looks like this: First I see the video (without audio), then the video freezes (showing the last image frame until the end) and after some seconds I hear the audio. I tried some things with CMSampleBufferSetOutputPresentationTimeStamp (subtracting the first CMSampleBufferGetPresentationTimeStamp from the current) for the audio, but it all didn't work and I don't think it is the right direction, since video & audio in the source movie should be in sync anyway... My setup in short: I create an AVAssetReader and 2 AVAssetReaderTrackOutput (one for video, one for audio) and add them to the AVAssetReader , then I create an AVAssetWriter and 2 AVAssetWriterInput (video & audio) and add them to the AVAssetWriter ... I start it all up with: [assetReader startReading]; [assetWriter startWriting]; [assetWriter startSessionAtSourceTime:kCMTimeZero]; Then I run 2 queues for doing the sample buffer stuff: dispatch_queue_t queueVideo=dispatch_queue_create("assetVideoWriterQueue", NULL); [assetWriterVideoInput requestMediaDataWhenReadyOnQueue:queueVideo usingBlock:^ { while([assetWriterVideoInput isReadyForMoreMediaData]) { CMSampleBufferRef sampleBuffer=[assetReaderVideoOutput copyNextSampleBuffer]; if(sampleBuffer) { [assetWriterVideoInput appendSampleBuffer:sampleBuffer]; CFRelease(sampleBuffer); } else { [assetWriterVideoInput markAsFinished]; dispatch_release(queueVideo); videoFinished=YES; break; } } }]; dispatch_queue_t queueAudio=dispatch_q

Tags (comma-separated) Cancel